pratt



G. R. PRATT. HEAT ENGINE.

APPLICATION FILED MAB-21, I918. 1,326,092.,

3 SHEETSSHEET 1- Patented Dec. 23,1919.

G. R. PRATT.

HEAT ENGINE. APPLICATION FILED MARIZI, 1918.

Patented Dec. 23,1919

3 SHEETS-SHEET 2- g-u liillil-li'll'iu FIWENWR Ari-vs G-.R.PRATT. 7 HEAT ENGINE.

APPLICATION FILED MAR. 21, 1918- Patented Dec. 23, 1919.

3 SHEETS-SHEET 3.

' GEORGE ROBERT PRATT, or wINNIrndMAnIToBA, CANADA.

HEAT-ENGINE.

Specification of Letters Patent.

Patented Dec. 23, 1919.

Application filed March 21, 1918. Serial No. 223,775.

To all whom it may concern:

Be it known that I, GEORGE ROBERT PRATT, of the city of Winnipeg, in the Province of Manitoba, Canada, have invented certain new and useful Improvements in Heat-Engines, of which the following is the specification. y

The invention relates to improvements in lleat engines in which the action of a gas under varying temperature conditions is utilized to do the work and the general object of the invention is to provide an eflicient, simple and easily controlled engine of this type.

A further object of the invention is to provide in a heat engine a displacer having a moving plunger separating the ends and arranged such'that the cool gas'is admitted to one end of the displacer ata low temperature and pressure and is passed out of that end through a heater, to the other end at a high temperature and pressure and is then expanded from the latter end to do work.

' With the above general object in view the invention consists essentially in the arrange ment and construction of parts hereinafter more particularly described and later pointed out in the appended claims, reference being had to the accompanying drawings in which Figure 1 represents a side view of a complete engine embodying my invention.

Fig. 2 represents a plan view of the same.

Fig. 3 represents a horiozntal longitudinal sectional view through the engine.

Fig. 4 represents a vertical sectional view centrally through the cooler employed.

Fig. 5 represents a vertical sectional view centrally through the heater employed.

Fig. 6"repr'esents an enlarged detailed sec tional view through the check valve.

Fig. 7'represents a vertical sectional view through the sliding valve casing."

Fig. 8 represents a horizontal sectional view through the valvecas'ing with the valve shown at the other end of, itstravel- In the drawings like characters of refer ence indicate corresponding parts in the several figures. -f '1 representsaoylinder with one end open and the other end closed by a' head 2 and 3 represents a piston operatively mounted in the cylinder and'fitted with a connecting rod 4 attached to a-crank'pin 5 carried by a pair ofcranksfi and. 7 mounted on the. mainsh'aft 8. The engine cylinder is suitably supported by pedestals 9 and 10 and the main shaft is rotatably mounted in suitable bearing's presented by the standards 11 and 12.

On the engine shaftI mount a fly wheel 13 and driving pulley 14 and also an eccentric 15.

16 represents a displacer having closed ends'l7 and 18 and alined axially with the cylinder 1. In the displacer I mount a plunger 19 which is directly connected 'by means of a stem 20 with the piston 3, the stem extending slidably through suitable bushings 21 and 22 supplied at the adjacent ends of the cylinder and displacer.

From this arrangement it will be apparent that the plunger and piston are connected in tandem.

The displacer 'is supported by suitable pedestals 23 and 24." To one-side of the cylinder I secure a cylindrical valve casing 25 in which I mount a slide valve 26 which has the stem 27 thereof extending through a suitable bushing 28 located at one end of the casing and fitted with a pair of spaced stop collars 29 and 80 and a sleeve 31 mounted on the stem to slide between the collars.

A valve rod 32 is pivotally connected at one end as indicated at 33 torthe sleeve 31 and has the opposite end constructed to form a strap 34 which is mounted on the eccentric 15. The throw of the eccentric is somewhat greater than the distance between the collars 29 and 80, so that in the rotation of the main shaft-the sleeve slides free of the stem for the greater part of its travel and is adapted to give the valve stem a slight kick at each end of the stroke. Theobject of this will be more apparent when the details of the slide valve are explained. The slide valve is more or less cylindrical in form and is fitted with two circumscribing grooves which form valve chambers 35 and 86 which are separated by the unaltered portions 37, 38 and 39 of the valve.

' 40' represents a cooler of any suitable design. It is shown in the present instance as embodying a casing '41 mounted on suitable legs and fitted with internal upper and lower cross plates'42 and 43 which provide between them a cooling chamber 44 and carry a plurality of vertically disposed tubes 45 passing through the cooling chamber.

The coolingchamber is designed to receive cooling water which is circulated through the cooling chamber by means of the water pipes 46 and 47.

. 48 represents a heater of any suitable construction such, in the present instance, embodying a casing 49 containing a heating coil 50 located above fire grates 51.

The valve casing is connected to the cool er by means of a pipe 52 which leads from the left hand end of the valve casing to the top of the cooler. An inlet pipe 53 is connect ed with the pipe 52 and is supplied with a suitable cut-01f valve 54. A further pipe 55 connects the bottom of the cooler with the valve casing, such opening to the interior of the valve casing in the particular location as shown best in Fig.

A further pipe 56 leads from the valve casing and connects with a T-elbow 57 which is connected to a pipe 58 which has one end opening as indicated at 59 to the right hand end of the displacer and the other end lead ing to the lower end of the coil 50. In this latter pipe between the elbow and the heater I introduce a check valve 60 which is arranged to open under pressure acting in the direction as indicated by the applied arrow (see Fig. 2), and closed under pressure in the opposite direction.

The upper end of the coil 50 is connected by means of a pipe 61 to the valve casing. The inner end of the displacer is connected by means of a pipe 62 to the valve casing and the inner end of the cylinder 1 is con nected by a pipe 63 to the valve casing.

I have not given a detailed description of the connections of the various pipes with the valve casing but I wish it to be noticed that these open to the valve casing in particular positions, which positions are as shown best in Figs. 3 and 7 of the drawings.

The entry ends of the pipes have to be arranged as shown in respect to one another and in respect to the valve and valve casing. The reason for this will be made clear when the operation of the engine is described.

Referring particularly to Figs. 1 and 3, it will be seen that the valve rod 32 is in its rearmost position and that in the turning of the main shaft in a right hand direction the eccentric will slide the sleeve along the valve stem without efiecting any movement thereof until it strikes the collar 30, at which time it will take the valve stem along with it to the end of the forward stroke of the valve rod. The travel given the stem is such that the valve 26 is brought to the position. shown in Fig. 8 of the drawings. The valve remains in this position for the greater part of the return stroke of the valve rod, that is until the sleeve strikes the collar 29 at which time the valve is again kicked, so to speak, to the returnposition as shown in Fig. 3.

The operation of this heat engine is as follows, assuming the valve 26 positioned initially as shown The system is first filledthrough the supply or entry pipe 53 with the gas at a certain temperature and pressure, say at a temperature of sixty degrees Fahrenheit and at a pressure of one hundred pounds per square inch. When the system is filled the valve 54: is closed. Assuming further that the heater and cooler are ready for operation with the capacity of the heater suflicient to raise the temperature of the gas passing through it from the initial temperature to say 520 F.

(thereby increasing its temperature) and the cooler of sufficient capacity to decrease the temperature of the gas passing through it to the initial temperature of 60 F.

In the positions shown the gas heated by the heater has been passed in a prior position of the valve as shown in Fig. 3 from the heater, through the pipe 61, to the pipe 62 and into the left hand end ofthe displacer and is expanding from the displacer through the pipe 60, through the valve chamber 35 and pipe 63 to the inner end of the cylinder where under the action of the expanding gas, the piston 3 is moved to the left. The gas, owing to the action of the piston, reduces in temperature and pressure. Concurrent with this action the gas from the cooler has been admitted by way of the pipe 55, chamber 36. pipes 56 and 58, to the outer end of the displacer and at the same initial temperature.

The movement of the piston efiects, owing to the rod 26, a simultaneous movement of the plunger and the movement just described is what might be called the working stroke of the piston. The return stroke is efiected by the momentum of the fly wheel 13 and on the return stroke the slide valve is moved to the opposite position as shown in Fig. 8 to close the passagebetween the cylinder and the displacer and to open the connection by way of the heater and between the opposite ends of the displacer.

The piston on the incoming or idle stroke ejects the gas in the cylinder by way of the pipe 63 and pipe 52 (see Fig. 8) to the cooler where the temperature is reduced to initial temperature and the cooled gas again passes through the system byway of the pipes 55, 56 and 58 to the displacer (the valve 60 at this time closino') and then out of the right hand end of the displacer by way of the pipe 58, through the heater, the pipe 61 and the pipe 62 to the left hand end of the displacer.

The gas passed to the out end of the displacer at original temperature and on the ingoing stroke of the plunger is, on the outgoing stroke, displaced to the opposite end of the displacer. In passing through the heater this gas has the temperature and pressure raised and the gas ultimately reaching the inner end of the displacer is at a hi h temperature and pressure. In expanding irom the displacer into the cylinder as hereinbefore disclosed the piston is forced out and commences the working stroke. This action continues as long as the engine is working and power is delivered from the engine at the pulley 14; by a belt or similar appliance.

The check valve 60 is provided to prevent the cool gas from the cooler passing directly to the heater before going into the displacer. That is to say that the gas from the cooler is first caused to enter the out end of the displacer on the ingoing stroke of the plunger and then to be displaced from the displacer directly to the heater and on the outgoing stroke of the plunger.

While I have described a particular sliding valve as controlling the opening and closing of the pipes, it will be readily understood that this could be modified without departing fromthe spirit of the invention as it is only one embodiment of a means for controlling the gas in the system at a proper time and between the cylinder, displacer, cooler and heater.

What I claim as my invention is 1. In a heat engine, a displacer having a plunger mounted for reciprocation therein, an inlet to one end of the displacer for a gas at low temperature and pressure, a heater,

a connection between the latter end of the displacer and the other end and by way of the heater whereby the gas passed from one end of the displacer to the other is heated in passing by the heater and enters the latter end of the displacer at a high temperature and pressure means permittlng of the release, expansion and exhausting of the gas from the latter end of the displacer and for utilizing the expanding gas prior to exhausting, to do work, and means for returning and readmitting the exhaust gases to the inlet end of the displacer at the original entry, temperature and pressure.

2. In a heat engine, a displacer having a moving plunger separating the ends and arranged such that gas admitted to one end of the displacer at a low temperature and pressure is passed out of that end to the other end thereof and a heater for heating the gas passed between the ends of the displacer whereby the gas upon reentering the end of the displacer will be at a high temperature and pressure.

3. ha heat engine, a displacer having closed ends and a plunger mounted therein for reciprocation within the displacer, a cooler, means for leading the gas at low temperature and pressure from the'cooler to the one end of the displacer, a heater, means for leading gas from the latter end of the displacer to the opposite end thereof and by way of the heater whereby the gas in passing is heated to a high temperature and pressure and admitted to the said opposite end of the displacer at a high temperature and pressure means permitting of the release, expansion and exhausting of the gas from the latter end of the displacer and for utilizing the expanding gas prior to exhausting, to

do work, and means for returning and readnnttmg the exhaust gases to the inlet end of the displacer at the original entry, temperature and pressure.

l. In a heat engine, a displacer having closed ends and a plunger mounted therein for reciprocation within the displacer, a cooler, means for leading the gas at low temperature and pressure from the cooler to the one end of the displacer, a heater, means for leading gas from the latter end of the displacer to the opposite end thereof and by way of the heater whereby the gas in passing is heated to a high temperature and pressure and admitted to the said opposite end of the displacer at a high temperature and pressure, a working cylinder, a piston in the cylinder, a connection between the latter end of the displacer at the cylinder to permit of the expanding of the gas from the displacer to the cylinder to actuate the piston, and a connection permitting the return to the cooler of the exhaust gases from the working cylinder.

Signed at Winnipeg, this 25 day of February, 1918.

GEORGE ROBERT PRATT. In the presence of- GERALD S. Roxnunerr, K. B. WAKEFIELD. 

